Processing apparatus, mold for wood processing, and method of processing wood

ABSTRACT

A processing apparatus for processing a wooden piece into a predetermined three-dimensional shape includes a first mold made of a material having at least one of viscosity and elasticity at least in a portion that abuts a surface of the wooden piece; and a second mold made of metal sandwiching the wooden piece with the first mold to apply compressive force on the wooden piece.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT international application Ser. No. PCT/JP2006/304216 filed Feb. 28, 2006 which designates the United States, incorporated herein by reference, and which claims the benefit of priority from Japanese Patent Applications No. 2005-106385, filed Apr. 1, 2005; No. 2005-139900, filed May 12, 2005; and No. 2005-149978, filed May 23, 2005, incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a processing apparatus, a mold, and a method for processing wood into a predetermined three-dimensional shape.

2. Description of the Related Art

In recent years, wood which is a natural material attracts attention. With a wide variety of grain patterns, wood products made of wood exhibit individual features depending on positions of the raw wood from which the particular wood products are cut out. Such individual features of each wood product give it a unique quality. In addition, surface damages and discoloration caused by a long-term use create unique textures which tend to evoke warm and familiar feeling in the user. Thus, the wood attracts attention as a material for products of uniqueness and taste which cannot be found in products made of synthetic resin or light metals. Techniques for processing wood are also developing dramatically.

According to one conventionally known technique for processing wooden pieces: a wooden board is softened with water absorption and compressed; the compressed wooden board is cut along a direction substantially parallel with a direction in which the compressive force is applied, whereby a primary fixed product with a sheet-like shape is obtained; and the primary fixed product is deformed into a desired three-dimensional shape under heat and moisture (for example, see Japanese Patent No. 3078452 Publication). Further, according to another conventional technique, a softened wooden board is compressed and temporarily secured in a prepared mold and left in the mold until the wooden board recovers. Thus a wood product with a desired shape can be obtained (see, for example, Japanese Patent Application Laid-Open No. H11-77619 Publication).

The fact that wooden pieces have individual features means that each taken-out wooden piece itself is not homogeneous by nature.

SUMMARY OF THE INVENTION

A processing apparatus according to one aspect of the present invention is for processing a wooden piece into a predetermined three-dimensional shape, and includes a first mold made of a material having at least one of viscosity and elasticity at least in a portion that abuts a surface of the wooden piece, and a second mold that is made of metal and sandwiches the wooden piece with the first mold to apply compressive force on the wooden piece.

A wood processing mold according to another aspect of the present invention is for processing a wooden piece into a predetermined three-dimensional shape by sandwiching the wooden piece with a metal mold to apply compressive force thereto, and includes a protrusion that abuts the surface of the wooden piece at compression of the wooden piece, and applies compressive force on the surface of the wooden piece while gradually expanding an abutting region of the surface from a central portion of the surface to a peripheral portion; and an end surface pressing portion that abuts an end surface of the wooden piece at compression of the wooden piece, and applies compressive force on the wooden piece in a direction substantially perpendicular to a thickness direction of the end surface. The protrusion and the end surface pressing portion are made of a material having at least one of viscosity and elasticity.

A method according to still another aspect of the present invention is for processing a wooden piece into a predetermined three-dimensional shape by applying compressive force on the wooden piece, and includes performing a compression process in which the wooden piece is compressed while a region of the wooden piece on which the compressive force acts is gradually expanded from a central portion to a peripheral portion.

A method according to still another aspect of the present invention is for processing a wooden piece into a predetermined three-dimensional shape by applying compressive force on the wooden piece, and includes performing a compression process in which the wooden piece is sandwiched and compressed between a first mold made of a material having at least one of viscosity and elasticity at least in a portion that abuts a surface of the wooden piece, and a second mold made of metal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a structure of a compressed wood product formed through a method of processing wood according to a first embodiment of the present invention;

FIG. 2 is a sectional view along line A-A of FIG. 1;

FIG. 3 is an explanatory diagram which schematically shows how a wooden piece is taken out from uncompressed raw wood;

FIG. 4 is an explanatory diagram which schematically shows how a wooden piece is processed in a primary compression process of the method of processing wood according to the first embodiment of the present invention;

FIG. 5 is a vertical sectional view of a wooden piece during compression in a primary compression process of the method of processing wood according to the first embodiment of the present invention;

FIG. 6 is a vertical sectional view which schematically shows how a wooden piece is processed in a secondary compression process (compression process) of the method of processing wood according to the first embodiment of the present invention where a mold for wood processing is being lowered;

FIG. 7 is a vertical sectional view which schematically shows how a wooden piece is processed in the secondary compression process (compression process) of the method of processing wood according to the first embodiment of the present invention where the mold for wood processing abuts the wooden piece;

FIG. 8 is a vertical sectional view of the wooden piece during compression in the secondary compression process;

FIG. 9 is a perspective view of an external structure of a digital camera in which the compressed wood product of FIG. 1 is employed as a jacket;

FIG. 10 is a perspective view of a structure of covers that constitute the exterior of the digital camera;

FIG. 11 is a perspective view of a structure of a compressed wood product formed through a method of processing wood according to a second embodiment of the present invention;

FIG. 12 is a sectional view along line C-C of FIG. 11;

FIG. 13 is a perspective view of a structure of a wooden piece before processing;

FIG. 14 is a sectional view along line E-E of FIG. 13;

FIG. 15 is a diagram which schematically shows how a wooden piece is taken out from raw wood;

FIG. 16 is a vertical sectional view of a structure of a mold for wood processing and main parts of a processing apparatus according to the second embodiment of the present invention;

FIG. 17 is a sectional view of a wooden piece sandwiched between the mold for wood processing and a metal mold;

FIG. 18 is a sectional view which schematically shows how a wooden piece is processed in a compression process of the method of processing wood according to the second embodiment of the present invention where deformation of the wooden piece is underway;

FIG. 19 is a sectional view which schematically shows how a wooden piece is processed in the compression process of the method of processing wood according to the second embodiment of the present invention where deformation of the wooden piece is completed;

FIG. 20 is a vertical sectional view which schematically shows how a wooden piece is processed in a shaping process of the method of processing wood according to the second embodiment of the present invention;

FIG. 21 is a vertical sectional view of a structure of a mold for wood processing and main parts of a processing apparatus according to a modification of the second embodiment of the present invention;

FIG. 22 is a perspective view of a structure of a compressed wood product formed through a method of processing wood according to a third embodiment of the present invention;

FIG. 23 is a sectional view along line G-G of FIG. 22;

FIG. 24 is a perspective view of a structure of a wooden piece before processing;

FIG. 25 is a sectional view along line I-I of FIG. 24;

FIG. 26 is a diagram which schematically shows how a wooden piece is taken out from raw wood;

FIG. 27 is a perspective view of a structure of main parts of a processing apparatus according to the third embodiment of the present invention;

FIG. 28 is a sectional view which schematically shows how a wooden piece is processed in a compression process of the method of processing wood according to the third embodiment of the present invention where an upper mold is starting to abut the wooden piece;

FIG. 29 is a sectional view which schematically shows how a wooden piece is processed in the compression process of the method of processing wood according to the third embodiment of the present invention where deformation of the wooden piece is underway;

FIG. 30 is a sectional view which schematically shows how a wooden piece is processed in the compression process of the method of processing wood according to the third embodiment of the present invention where deformation of the wooden piece is completed;

FIG. 31 is a vertical sectional view which schematically shows how a wooden piece is processed in a shaping process of the method of processing wood according to the third embodiment of the present invention;

FIG. 32 is a perspective view of a structure of an upper mold (first mold) constituting a part of a processing apparatus according to a fourth embodiment of the present invention;

FIG. 33 is a sectional view along line L-L of FIG. 32;

FIG. 34 is a sectional view which schematically shows how a wooden piece is compressed by the processing apparatus according to the fourth embodiment of the present invention where the upper mold is starting to abut the wooden piece with an illustration of main parts of the processing apparatus;

FIG. 35 is a sectional view which schematically shows how a wooden piece is processed in the compression process of the method of processing wood according to the fourth embodiment of the present invention where deformation of the wooden piece is underway; and

FIG. 36 is a sectional view which schematically shows how a wooden piece is processed in the compression process of the method of processing wood according to the fourth embodiment of the present invention where deformation of the wooden piece is completed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, exemplary embodiments of the present invention (hereinbelow simply referred to as embodiments) will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view of a structure of a compressed wood product formed through a method of processing wood according to a first embodiment of the present invention. FIG. 2 is a sectional view along line A-A of FIG. 1. A compressed wood product 1 shown in FIGS. 1 and 2 includes a main plate 1 a which has a substantially rectangular surface, two side plates 1 b that extend from respective long sides of the main plate 1 a forming a predetermined angle with the main plate 1 a, and two side plates 1 c that extend from respective short sides of the main plate 1 a forming a predetermined angle with the main plate 1 a. The entire compressed wood product 1 is of a substantially bowl-like shape. Thickness (hereinbelow indicated by a reference character “r”) of the compressed wood product 1 is substantially uniform. A section taken along line B-B of FIG. 1 has substantially the same shape as a section taken along line A-A of FIG. 2 other than dimension.

A method of processing wood according to the first embodiment will be described. In the description below, manufacture of the compressed wood product 1 with the above-described structure will be described. It should be noted, however, that the method of processing wood according to the first embodiment is obviously applicable to compressed wood products with different structures.

First, a wooden piece, which is a material for the compressed wood product 1, is taken out from uncompressed raw wood. FIG. 3 is an explanatory diagram which schematically how the wooden piece, which is a material for the compressed wood product 1, is taken out from the raw wood. In the taking-out process, a substantially bowl-like wooden piece 51 is taken out from the raw wood 50 so that the taken-out wooden piece 51 is larger in volume than a finished product by an amount to be decreased in a compression process described later. The wooden piece 51 thus taken out has a main plate 51 a, side plates 51 b, and side plates 51 c corresponding to the main plate 1 a, the side plates 1 b, and side plates 1 c of the compressed wood product 1 shown in FIG. 1, respectively, and has a substantially uniform thickness (hereinafter the thickness of the wooden piece 51 is indicated by reference character “r₀”) over the whole piece.

In FIG. 3, simply as an illustrative example, a lengthwise direction of the wooden piece 51 taken out from the raw wood 50 and a direction L of wooden fibers of the wooden piece 51 are shown to be substantially parallel with each other, and the main plate 51 a has a straight grain surface. Alternatively, the wooden piece 51 can be taken out so that the lengthwise direction thereof is substantially parallel with the direction L of wooden fibers of the wooden piece 51 and yet the main plate 51 a has a flat grain surface or a surface with intermediate grain pattern of flat grain and straight grain. In the first embodiment, the wooden piece 51 can be taken out in a most suitable manner from the raw wood 50 in view of required strength, appearance, or the like of the wooden piece. Hence, in the drawings referred to in the following description, grain 50G is not particularly shown.

In the taking-out process, a plate-like wooden piece may be taken out so that the lengthwise direction thereof is substantially parallel with the direction of wooden fibers of the raw wood 50. The raw wood 50 employed in the first embodiment can be selected from, for example, Japanese cypress, hiba cedar, paulownia, Japanese cedar, pine, cherry, zelkova, ebony wood, bamboo, teak, mahogany, and rosewood, as most appropriate for the purpose of use of the compressed wood product 1.

Thereafter, the wooden piece 51 taken out in the taking-out process is compressed. In the first embodiment, the wooden piece 51 is compressed in two separate steps. In performing the compression, the wooden piece 51 is first left in a water vapor atmosphere in high temperature and high pressure for a predetermined time period. In the description, “high temperature” means temperatures in a range of approximately 100 to 230 degrees Centigrade (° C.), and more preferably temperatures in a range of approximately 180 to 230° C., and “high pressure” means pressures in a range of approximately 0.1 to 3 Megapascal (MPa), and more preferably pressures in a range of approximately 0.45 to 2.5 MPa. Thus, the wooden piece 51 absorbs water in excess to be softened.

Then, a first compression is performed in the same water vapor atmosphere (primary compression process). FIG. 4 is an explanatory diagram showing how the first compression process is performed and is a vertical sectional view of the wooden piece 51 along a similar section to in FIG. 2. As shown in FIG. 4, in the primary compression process, the wooden piece 51 to be compressed is sandwiched between a pair of metal molds 61 and 71 that have corresponding shapes to a desired finished shape of the wooden piece 51, and a compressive force of a predetermined level is applied to the sandwiched wooden piece 51 by the metal molds 61 and 71.

Of the two metal molds 61 and 71, the metal mold 61 used to apply compressive force to the wooden piece 51 from above the wooden piece 51 during compression has a downward protrusion 62. Side surfaces of the protrusion 62 have substantially the same shapes as internal surfaces of the side plates 51 b and 51 c of the wooden piece 51. Further, downward projection height H of the protrusion 62 is larger than a depth h of the internal surface of the bowl-like wooden piece 51 (H>h). On the other hand, the metal mold 71 used to apply compressive force to the wooden piece 51 from below the wooden piece 51 during compression has a downward depression 72. The shape of the depression 72 is substantially the same as the external surfaces of side plates 51 b and 51 c.

FIG. 5 is a sectional view of the wooden piece 51 sandwiched and compressed between the two metal molds 61 and 71 after the metal mold 61 is lowered so as to approach the metal mold 71 from the state shown in FIG. 4, and is a sectional view along the same section as in FIG. 4. As shown in FIG. 5, the wooden piece 51 is deformed into a three-dimensional shape corresponding to a gap formed between the protrusion 62 and the depression 72.

In the primary compression process, since the protrusion 62 and the depression 72 are of the above-described shape, a large compressive force acts on the main plate 51 a whose thickness direction is substantially parallel with a direction of action of the compressive force, whereby a thickness r₁ of the wooden piece 51 after the compression is smaller than the thickness r₀ prior to the compression. On the other hand, since only a little compressive force is applied on the side plates 51 b and 51 c, the thickness thereof after the compression remains r₀. As a result, the thickness r₁ of the main plate 51 a becomes smaller than the thickness r₀ of the side plates 51 b and 51 c after the primary compression process (r₁<r₀). A compression rate of the main plate 51 a can be set to optimal value in view of the material of the wooden piece 51 and the purpose of use of the compressed wood product 1. According to the set compression rate, the shape of the wooden piece 51 (thickness r₀, depth h, or the like) and the shapes of the metal molds 61 and 71 (downward projection height H of the protrusion 62, or the like) are determined.

In the specification, “compression rate” is defined as a ratio of a decreased amount of thickness of the wooden piece through compression to a thickness of the wooden piece before the compression. For example, when a wooden piece with a thickness R₀ is compressed to a thickness R (<R₀), the compression rate can be represented as (R₀−R)/R₀.

After the wooden piece 51 is left in the compressed state shown in FIG. 5 for a predetermined time period, the metal mold 61 is lifted to release a wooden piece 51′ subjected to the primary compression process. Thereafter, another mold 81 is lowered to sandwich and compress the wooden piece 51′ between the mold 81 (first mold) and the metal mold 71 (second mold) (compression process). The compression process is also performed in the same water vapor atmosphere as the primary compression process. In distinction from the primary compression process, the compression process here in the first embodiment is referred to as a secondary compression process hereinbelow.

FIGS. 6 to 8 are explanatory views which schematically show how the secondary compression process is performed with the processing apparatus according to the first embodiment of the present invention. FIGS. 6 to 8 are vertical sectional views of the wooden piece 51′ along a section corresponding to the section of the wooden piece 51 shown in FIGS. 4 and 5.

A structure of main parts of the processing apparatus according to the first embodiment will be described. The processing apparatus according to the first embodiment includes a mold 81 (first mold), and a mold 71 (second mold) which sandwiches the wooden piece 51′ with the mold 81 to apply compressive force to the wooden piece 51′. The mold 81 which is a mold for wood processing according to the first embodiment includes a rubber mold 82 which is made of a material such as silicon rubber and which serves to abut an internal surface of the wooden piece 51′ to apply compressive force thereto, a substantially rectangular solid metal mold 83 which is adhered to an upper end of the rubber mold 82, and a metal mold 84 which surrounds the metal mold 83 and which abuts upper ends of the side plates 51′b and 51′c of the wooden piece 51′ at a bottom surface thereof during the secondary compression process. The metal mold 83 is vertically movable relative to the metal mold 84.

The rubber mold 82 is tapered so that the horizontal width thereof slightly decreases downward as shown in FIG. 6. The bottom surface of the rubber mold 82 is substantially rectangular whose area is slightly smaller than that of the internal surface of the main plate 51′a of the wooden piece 51′ fit into the depression 72 of the mold 71. An inner periphery of the bottom surface of the metal mold 84 is rounded at a corner.

As the mold 81 with the above-described structure is lowered down toward the wooden piece 51′, the bottom surface of the rubber mold 82 comes to abut the main plate 51′a of the wooden piece 51′ as shown in FIG. 7. In this state, there is still a gap between the rubber mold 82 and the wooden piece 51′. Thereafter, as the metal mold 83 is further lowered down, which is vertically movable with respect to the metal mold 84 which remains still, the rubber mold 82 is pushed in a vertical direction and deformed. Then, an area of the wooden piece 51′ in contact with the rubber mold 82 gradually increases from a center to a periphery of the main plate 51′a, whereby the gap between the rubber mold 82 and the wooden piece 51′ is gradually filled up. The tapered shape of the rubber mold 82 and the round shape of the corner of the inner periphery of the bottom surface of the metal mold 84 serve to allow for smooth deformation of the rubber mold 82.

When the gap between the wooden piece 51′ and the mold 81 is completely filled with the rubber mold 82, and the rubber mold 82 comes to a position where a predetermined compressive force may be applied to the wooden piece 51′, the lowering of the metal mold 83 is stopped and the metal mold 83 is maintained at the position for a predetermined time period. FIG. 8 is a diagram schematically showing the wooden piece 51′ compressed by the rubber mold 82. In the state as shown in FIG. 8, the rubber mold 82 is applying a uniform compressive force to every position of the wooden piece 51′ due to a characteristic of the rubber mold 82.

After the wooden piece 51′ is left in the state as shown in FIG. 8 for a predetermined time period, the wooden piece 51′ is released from compression and dried. Thus, the compressed wood product 1 shown in FIGS. 1 and 2 is finished. Through the two compression processes, the density (specific gravity) as well as the strength of the compressed wood product 1 becomes substantially uniform. An average value of the compression rate in the thickness direction (average compression rate) of the compressed wood product 1 made of the wooden piece 51 is approximately in a range of 0.5 to 0.7, and the thickness r shown in FIG. 2 is approximately in a range of 30% to 50% of the thickness r₀ of the wooden piece 51 taken out from the raw wood 50 prior to the compression (see FIG. 4).

In the specification, “average compression rate” is defined as a value of arithmetic average of compression rates, when a compressed wooden piece exhibits different compression rates at different portions.

Here, the average compression rate in the secondary compression process in which the finished shape of the compressed wood product 1 is determined is preferably higher than the average compression rate in the primary compression process. In the primary compression process of the first embodiment, since the compression rate of the main plate is (r₀−r₁)/r₀, and the compression rate of the side plates is zero, the average compression rate is (r₀−r₁)/2r₀. On the other hand, in the secondary compression process, since the compression rate of the main plate is (r₁−r)/r₁, and the compression rate of the side plates is (r₀−r)/r₀, the average compression rate is {(r₀(r₁−r)+r₁(r₀−r)}/2r₀r₁. Hence, the condition for the average compression rate in the secondary compression process to exceed the average compression rate in the primary compression process is r₁>r. In other words, in order to make the average compression rate in the secondary compression process higher than the average compression rate in the primary compression process in the formation of the compressed wood product 1 from the wooden piece 51, it is sufficient that the main plate is thinned in the secondary compression process.

FIG. 9 is a perspective view of an example of application of the compressed wood product 1 formed as described above, and more particularly is a perspective view of an external structure of a digital camera in which the compressed wood product 1 is employed as a jacket. A digital camera 100 shown in FIG. 9 includes a casing-like jacket provided by combining two covers 2 and 3 formed from the compressed wood product 1. The compressed wood product 1 is processed so as to have an opening, a cut-out portion or the like as appropriate, to serve as the covers 2 and 3. The jacket houses various electronic elements and optical elements (not shown) for realizing functions of the digital camera 100. Such electronic elements and optical elements are, for example, a control circuit that controls driving related to imaging process or the like, a solid-state imaging device such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and an audio device such as a microphone or a speaker for input/output of sound.

FIG. 10 is a perspective view of a schematic structure of the covers 2 and 3. As shown in FIG. 10, the covers 2 and 3 are formed from the compressed wood product 1 which is provided with an opening or a cut-out portion as appropriate. A main plate 2 a of the cover 2 includes a circular cylindrical opening 21 to expose an imaging unit 4 having an image pick-up lens, and a rectangular solid opening 22 to expose a photoflash 5. Side plates 2 b and 2 c of the cover 2 have a semi-circular cylindrical cut-out portion 23 and a rectangular solid cut-out portion 24, respectively. The covers 2 and 3 have substantially uniform thickness, of which the value is more preferably approximately 1.6 millimeters (mm).

On the other hand, a main plate 3 a of the cover 3 has a rectangular solid opening 31 to expose a display unit 6 which is implemented by a liquid crystal display, a plasma display, or an organic electroluminescence (EL) display, or the like for display of image information or textual information. A side plate 3 b of the cover 3 has a semi-circular cylindrical cut-out portion 32, which forms an opening 41 to expose a shutter button 7 together with the cut-out portion 23 of the cover 2. Further, a side plate 3 c has a cut-out portion 33, which forms an opening 42 to expose a connection interface (e.g., DC input terminal, USB connection terminal) to an external device, together with the cut-out portion 24 of the cover 2.

The openings or the cut-out portions mentioned above may be formed simultaneously with the taking-out of the wooden piece from the raw wood 50. Alternatively, they may be formed via cutting or punching after the primary compression process or the secondary compression process. Alternatively, further openings may be provided at an appropriate position to attach a finder or to expose an operation key from which the user can input an operation instruction signal. Still alternatively, an audio output hole may be provided at an appropriate position to output sounds generated by an embedded speaker in the jacket.

When the compressed wood product 1 is applied as the jacket of the digital camera 100 as described above, grains and unevenness of wood exposed on a surface of the jacket serve as antislip, whereby the operability of the digital camera 100 can be enhanced. Thus, the compressed wood product manufactured by the method of processing wood according to the first embodiment can be applied as a jacket material to various electronic devices other than a digital camera, such as a portable communication terminal such as a portable telephone, a personal handyphone system (PHS) or a personal digital assistant (PDA), a portable audio device, an IC recorder, a portable television, a portable radio, remote controls for various home appliances, and a digital video.

According to the first embodiment of the present invention as described above, in the first mold, at least a portion which abuts the surface of the wooden piece to be processed is made of a material having at least one of viscosity and elasticity, and the second mold is made of metal. The wooden piece is sandwiched and compressed between the first and the second molds, whereby the density of the wooden piece can be made uniform regardless of the shape of the wooden piece to be processed. As a result, the uniform strength can be granted to the wooden piece after the compression regardless of the shape thereof.

Further, according to the first embodiment, the residual stress inside the wooden piece after the compression can be decreased to manufacture the compressed wood product with high shape stability which is hard to break and less likely to change in shape over time. In particular, with the use of the rubber mold in the compression process, the compressive force can be uniformly applied and generation of cracks or the like can be prevented even in a portion, such as a knurl of wood, which is harder than other portions and more likely to cause cracks in the compression by the metal molds, whereby the improvement in yield can be achieved.

The secondary compression process with the rubber mold may be performed immediately after the taking-out process of wood without the primary compression process.

Alternatively, a shaping process may be further performed to the wooden piece-after the secondary compression process, so that the wooden piece takes a more conforming shape to a desired shape. The shaping process may be realized as a tertiary compression process (finishing compression process) where a predetermined metal mold with higher dimensional accuracy than the rubber mold is employed in the same water vapor atmosphere as employed in the primary or the secondary compression process. Through such tertiary compression process, the wooden piece can be given form to a predetermined shape with higher accuracy.

Alternatively, the shaping process may be realized as a surface cutting process where the surface of the wooden piece is shaped via cutting. The cutting process is suitable when the wooden piece has a knurl portion which remains thicker than other portions of the wooden piece and which is desired to be flat. Through such cutting process, similarly to the tertiary compression process, the wooden piece can be given form to a predetermined shape with higher accuracy. Here, both the tertiary compression process and the cutting process may be performed as the shaping process in an arbitrary order. Further, the shaping process can be performed after the compression process when the compression process is performed with the rubber mold immediately after the taking-out process described above.

In the first embodiment, the rubber mold which is a elastic body is employed for application of compressive force to the wooden piece in the secondary compression process. However, a mold made of other material such as a viscoelastic body containing more general polymer gel or clay is also applicable in place of the rubber mold. In other words, a mold which is made of a material having at least one of viscosity and elasticity can be applied as the mold 81.

FIG. 11 is a perspective view of a structure of a compressed wood product formed through a method of processing wood according to a second embodiment of the present invention. FIG. 12 is a sectional view along line C-C shown in FIG. 11. A compressed wood product 11 shown in FIGS. 11 and 12 includes a main plate 11 a which has a substantially rectangular surface, two side plates 11 b that extend from respective sides substantially parallel with a lengthwise direction of the main plate 11 a forming a predetermined angle with the main plate 11 a, and two side plates 11 c that extend from respective sides substantially parallel with a breadthwise direction of the main plate 11 a forming a predetermined angle with the main plate 11 a. The thickness (indicated by r₂) of the compressed wood product 11 is substantially uniform, and the main plate 11 a has a flat grain surface. A section taken along line D-D of FIG. 11 has substantially the same shape as the section taken along line C-C shown in FIG. 12 other than dimension.

A method of processing wood according to the second embodiment will be described. In the description below, manufacture of the compressed wood product 11 with the above-described shape will be described. It should be noted, however, that the method of processing wood according to the second embodiment is obviously applicable to compressed wood products with different shapes.

First, a wooden piece, which is a material for the compressed wood product 11, is taken out from raw wood. FIG. 13 is a perspective view of a structure of a wooden piece taken out from the uncompressed raw wood by cutting or the like. FIG. 14 is a sectional view along line E-E of FIG. 13. A wooden piece 111 shown in the drawings is more bowl-like than the shaped compressed wood product 11 (see FIG. 11) and an external surface 111 a and an internal surface 111 b thereof are smooth curved surfaces with a substantially uniform thickness (indicated by r₃). The wooden piece 111 is larger in volume than a finished product by an amount to be decreased in a compression process described later. The section taken along line F-F of FIG. 13 has substantially the same shape as the section taken along line E-E shown in FIG. 14 other than dimension.

FIG. 15 is a schematic diagram showing a position from which the wooden piece 111 with the above described structure is taken out, and more particularly is a schematic sectional view showing a position in the raw wood 50 corresponding to the section shown in FIG. 14. In order to manufacture the compressed wood product 11 with the main plate 11 a having a flat grain surface as shown in FIG. 11, the wooden piece 111 must be taken out from the raw wood so as to have a flat grain surface. Hence, at the taking out of the wooden piece 111 from the raw wood 50, the wooden piece 111 is taken out so that a curvature of the side surface of the wooden piece 111 is generally larger than a curvature of the grain 50G as shown in FIG. 15.

Alternatively, a straight grain wooden piece or a wooden piece having an intermediate grain pattern between the flat grain and the straight grain can be employed as the wooden piece 111. Thus, a manner of taking out a wooden piece to be processed from the raw wood 50 can be determined according to various conditions such as a purpose of use of a compressed wood product manufactured from the wooden piece, required strength, appearance, or the like of the compressed wood product.

Subsequently, the wooden piece 111 taken out as described above is compressed (compression process). Prior to the compression process, the wooden piece 111 is left in the same water vapor atmosphere of high temperature and high pressure as in the first embodiment for a predetermined time period. Thus, the wooden piece 111 absorbs water in excess to be softened. Alternatively, however, the wooden piece 111 may be heated by high-frequency electromagnetic waves such as microwaves before compression, for example.

Thereafter, the wooden piece 111 is compressed in the same water vapor atmosphere as described above. FIG. 16 is a vertical sectional view of a structure of a mold for wood processing and main parts of a processing apparatus according to the second embodiment, and schematically showing how the compression process is performed. As shown in FIG. 16, the processing apparatus according to the second embodiment includes a mold 131 and a metal mold 141 that sandwich the wooden piece 111 to be processed and apply compressive force thereto. Here in FIG. 16, the section of the wooden piece 111 is shown reversed from the section in FIG. 14. In FIG. 16, the internal surface 111 b of the wooden piece 111 is shown above the external surface llla.

The mold 131 which is the mold for wood processing according to the second embodiment includes a rubber mold 132 that is made of a material such as silicon rubber (elastic body) and that abuts the internal surface 111 b which is one of the surfaces of the wooden piece 111, and a substantially rectangular solid movable metal mold 133 that is adhered to an upper end of the rubber mold 132 and movable in the vertical direction. The rubber mold 132 includes a protrusion 134 that protrudes downwards in FIG. 16 and abuts at least a portion of the internal surface 111 b of the wooden piece 111, and an end surface pressing portion 135 that holds the end surface 111 c of the wooden piece 111 and applies compressive force to the end surface 111 c in a direction substantially perpendicular to the thickness direction of the end surface 111 c at compression. Here, the deformation of the rubber mold 132 may be restricted by provision of a metal mold on an outer periphery of the rubber mold 132 depending on hardness of the employed rubber mold 132.

The metal mold 141 which applies compressive force to the wooden piece 111 from below at the time of compression has a depression 142 which fits the external surface 111 a of the wooden piece 111. An edge 143 of the depression 142 is rounded, whereby the crack is prevented from being generated in the wooden piece 111 by the excessive application of stress to a portion in the external surface 111 a that abuts the edge 143 in the external surface 111 a at the compression of the wooden piece 111.

FIG. 17 is a sectional view of the rubber mold 132 and the metal mold 141 where the mold 131 is lowered so that the rubber mold 132 may abut the metal mold 141. As shown in FIG. 17, the external surface 111 a of the wooden piece 111 abuts a central portion of the depression 142 of the metal mold 141. A neighborhood of the lower end portion of the protrusion 134 abuts the central portion of the internal surface 111 b of the wooden piece 111. Since the shape of the external surface 111 a largely differs from the shape of the depression 142, a gap is formed between a peripheral portion of the external surface 111 a and the depression 142 in this state. On the other hand, the shape of the internal surface 111 b does not perfectly match with the shape of the protrusion 134, though the difference between the shape of the internal surface 111 b and that of the protrusion 134 is not as notable as the difference between the shape of the external surface 111 a and that of the depression 142. Thus, a gap is also formed between a peripheral portion of the internal surface 111 b and the protrusion 134. As a result, immediately after the metal mold 131 starts to be lowered from the state shown in FIG. 17, the compressive force acts only on the neighborhood of the central portion of the wooden piece 111.

FIG. 18 is a sectional view of the mold 131 on the way to being lowered down from the state shown in FIG. 17. As shown in FIG. 18, as the mold 131 is lowered, the rubber mold 132 itself is pressed by the movable metal mold 133 and the wooden piece 111 to be gradually deformed, and a region of the internal surface 111 b brought into contact with the rubber mold 132 gradually expands from the central portion to the peripheral portion of the surface of the wooden piece 111. Simultaneously, the end surface pressing portion 135 of the rubber mold 132 abuts the end surface 111 c to apply compressive force thereto in a direction perpendicular to the thickness direction of the end surface 111 c. As a result, a region on which the compressive force acts on the surface of the wooden piece 111 gradually expands as the mold 131 is lowered, whereby the gap between the external surface 111 a and the metal mold 141, and the gap between the internal surface 111 b and the rubber mold 132 gradually decrease with the deformation. At the same time, the thickness of the wooden piece 111 gradually decreases from the central portion to the peripheral portion.

At the deformation, the external surface 111 a is deformed while abutting and sliding on the edge 143. The surface of the edge 143 is preferably coated with a material such as Teflon (registered trademark) or the like to decrease the dynamic friction force generated between the edge 143 and the wooden piece 111 and to further facilitate the sliding movement of the wooden piece 111. The provision of such coating is also preferable for the prevention of crack.

As described above, by applying the rubber mold 132 to the mold 131 sandwiching the wooden piece 111, a gradual deformation of the rubber mold 132 at the compression serves to alleviate a sudden deformation of the wooden piece 111. Hence, in contrast to the conventional technique where the wooden piece is sandwiched and compressed by a pair of metal molds, the wooden piece 111 is not subjected to an excessive application of compressive force, whereby even when the deformation of the wooden piece through the compression is substantial, the crack or the like can be prevented from being generated in the wooden piece 111.

Thereafter, the rubber mold 132 completely fills the gap between the wooden piece 111 and the rubber mold 132, and applies a predetermined compressive force to the wooden piece 111. Then, the lowering of the movable metal mold 133 is stopped. FIG. 19 is a sectional view of the wooden piece 111 in the compression process where the deformation of the wooden piece 111 is nearly finished. In the state as shown in FIG. 19, a uniform compressive force is applied from the rubber mold 132 to the entire wooden piece 111 regardless of the position due to characteristics of the rubber mold 132 as an elastic body. After being left for a predetermined time period in the state as shown in FIG. 19, the mold 131 is separated from the metal mold 141.

Subsequently, a metal mold (hereinafter referred to as a shaping metal mold) which is employed for shaping and is different from the mold 131 is lowered down in the same water vapor atmosphere as in the compression process described above, and the wooden piece 111 is sandwiched between the shaping metal mold and the metal mold 141 to be shaped (shaping process). FIG. 20 is a sectional view of the wooden piece 111 being compressed in the shaping process where the deformation of the wooden piece 111 is nearly finished, and is a vertical sectional view along the same section as in FIG. 17.

A shaping metal mold 151 which applies compressive force to the wooden piece 111 from above in the shaping process has a protrusion 152 which fits the internal surface 111 b of the wooden piece 111. The protrusion 152 is formed so that the portion which is not sufficiently compressed by the rubber mold 132 in the above-described compression process, for example, a vicinity of the end surface 111 c of the wooden piece 111, is properly shaped. After the wooden piece 111 is left in the compressed state as shown in FIG. 20 for a predetermined time period, the metal mold 141 is separated from the metal mold 151 to release the wooden piece 111 from compression and water vapor atmosphere, and then the wooden piece 111 is dried. Thus, the compressed wood product 11 shown in FIG. 11 is finished.

After the compression process and the shaping process, the thickness r₂ of the compressed wood product 11 is approximately 30% to 50% of the thickness r₃ of the uncompressed wooden piece 111 taken out from the raw wood 50. In other words, a compression rate (r₃−r₂)/r₃ of the wooden piece is approximately in a range of 0.5 to 0.7. The compression rate in the compression process and the shaping process can be varied with the wood species of the wooden piece 111, the purpose of use of the compressed wood product 11 or the like. For example, the thickness may not be substantially changed and only the shape of the wooden piece may be notably changed in the compression process, whereas the wooden piece may be compressed mainly in the thickness direction in the shaping process.

Depending on the shape and the purpose of use of the compressed wood product to be processed, a desired three-dimensional shape of the wooden piece may be obtained with a sufficient accuracy merely by the compression process. Then, the shaping process is not always necessary.

In the two processes as described above (compression process, shaping process), the processing apparatus may be provided with a driving unit for electrically driving the mold 131 or the shaping metal mold 151 to realize the vertical movement of the mold 131 or the shaping metal mold 151 relative to the metal mold 141, so that the mold 131 or the shaping metal mold 151 can be electrically driven and the compressive force applied to the wooden piece 111 can be controlled. Alternatively, the mold 131 or the shaping metal mold 151 may be screwed on the metal mold 141, so that the vertical movement of the mold 131 or the shaping metal mold 151 relative to the metal mold 141 can be realized with manual or automatic screwing and the compressive force applied to the wooden piece 111 can be controlled.

Still alternatively, the surface of the wooden piece to be processed may be shaped by cutting in the shaping process. The cutting process is suitable when the wooden piece after compression process has a knurl portion which remains thicker than other portions of the wooden piece and which is desired to be flat.

The water vapor atmosphere of high temperature and high pressure in the compression process can be realized, for example, inside a pressure container. Then, since there is only a limited space in the pressure container, a stroke of the mold or the metal mold to be driven cannot be set long. When the mold 131 as described above is employed, however, since the rubber mold 132 is deformed, the stroke can be set longer than an ordinary metal mold, whereby the compressive force can be more freely applied even in a limited space.

According to the second embodiment of the present invention as described above, when the compressive force is applied to the wooden piece to be processed, the region on which the compressive force acts gradually expands from the central portion to the peripheral portion of the wooden piece during the compression. Hence, even when the deformation of the wooden piece by the compression is substantial, the wooden piece of a desired shape can be manufactured without generation of cracks. As a result, the yield of the production of the compressed wood product can be improved.

Further, according to the second embodiment, since the mold for wood processing includes the rubber mold, the rubber mold is deformed at the time of compression so as to apply uniform compressive force to the entire surface of the wooden piece. Hence, the density of the wooden piece can be made uniform regardless of the shape of the wooden piece to be processed and the compressed wooden piece can be granted with a uniform strength.

Next, a modification of the second embodiment will be described. FIG. 21 is a vertical sectional view of a structure of a mold for wood processing and main parts of a processing apparatus according to the modification of the second embodiment, and is a diagram schematically showing how a compression process is performed where a planar wooden piece 112 taken out from the raw wood 50 is compressed. A mold 161 (mold for wood processing) which is used to apply compressive force to the wooden piece 112 from above the wooden piece 112, includes a rubber mold 162, and a substantially rectangular solid movable metal mold 163 adhered to an upper end of the rubber mold 162. The metal mold 141 employed to apply compressive force to the wooden piece 112 from below the wooden piece 112 is the same as in the second embodiment described above.

The rubber mold 162 which is a part of the mold 161 includes, a protrusion 164 which abuts a central portion of one of the surfaces (upper surface in FIG. 21) of the planar wooden piece 112 immediately before the application of compressive force, and an end surface pressing portion 165 which abuts an end surface of the wooden piece 112 at the time of compression, and applies compressive force to the end surface in a direction substantially perpendicular to the thickness direction of the end surface.

When the movable metal mold 163 is lowered down from the state shown in FIG. 21, the protrusion 164 of the rubber mold 162 is deformed of itself so as to gradually expand a region where the rubber mold 162 makes contact with the surface of the wooden piece 112 from the central portion to the peripheral portion of the wooden piece 112, thereby deforming the wooden piece 112. When the central portion of the lower surface of the wooden piece 112 abuts the depression 142, the compressive force starts to act on the central portion of the wooden piece in its thickness direction, thinning the wooden piece 112. Thereafter, as the region of the lower surface of the wooden piece 112 which abuts the depression 142 gradually expands to the peripheral portion, the region where the compressive force acts gradually expands as well. Here, the end surface pressing portion 165 continues to apply compressive force to the end surface of the wooden piece 112 as described above. In the end, the entire lower surface of the wooden piece 112 abuts the depression 142 of the metal mold 141, until the wooden piece 112 comes to have a sectional shape as shown in FIG. 19. A subsequent process is the same as that in the second embodiment (including the shaping process).

Here, in place of the rubber mold which is an elastic body, a mold made of other material such as a viscoelastic body containing more general polymer gel can be employed as the mold for wood processing. In other words, a material having at least one of viscosity and elasticity may be employed as a material of the mold for wood processing in a portion abutting the wooden piece to be processed.

FIG. 22 is a schematic perspective view of a structure of a compressed wood product formed through a method of processing wood according to a third embodiment of the present invention. FIG. 23 is a sectional view along line G-G of FIG. 22. A compressed wood product 12 shown in FIGS. 22 and 23, includes a main plate 12 a which has a substantially rectangular surface, two side plates 12 b that extend from respective sides substantially parallel with a lengthwise direction of the main plate 12 a forming a predetermined angle with the main plate 12 a, and two side plates 12 c that extend from respective sides substantially parallel with a breadthwise direction of the main plate 12 a forming a predetermined angle with the main plate 12 a. The thickness (indicated by r₄) of the compressed wood product 12 is substantially uniform, and the main plate 12 has a flat grain surface. A section taken along line H-H of FIG. 22 has substantially the same shape as a section taken along line G-G of FIG. 23 other than dimension.

Next, the method of processing wood employed for the formation of the compressed wood product 12 will be described. In the description below, manufacture of the compressed wood product 12 with the above-described shape will be described. It should be noted, however, that the method of processing wood described here is obviously applicable to compressed wood products with different shapes.

First, a wooden piece, which is a material for the compressed wood product 12, is taken out from raw wood. FIG. 24 is a perspective view of a schematic structure of a wooden piece taken out from the uncompressed raw wood by cutting or the like before processing. FIG. 25 is a sectional view along line I-I of FIG. 24. A wooden piece 211 shown in the drawings is more bowl-like than the shaped compressed wood product 12 (see FIG. 22) and an external surface 211 a and an internal surface 211 b thereof are smooth curved surfaces with a substantially uniform thickness (indicated by r₅). An external shape of the wooden piece 211 is substantially like a rectangle with round corners in a plan view (viewed from above in FIG. 25). The wooden piece 211 is larger in volume than a finished product by an amount to be decreased in a compression process described later. A section taken along line J-J of FIG. 24 has substantially the same shape as a section taken along line I-I of FIG. 25 other than dimension.

FIG. 26 is a schematic diagram showing a position from which the wooden piece 211 with the above described structure is taken out, and more particularly is a sectional view schematically showing a position in the raw wood corresponding to the section shown in FIG. 25. In order to manufacture the compressed wood product 12 with the main plate 12 a having a flat grain surface as shown in FIG. 22, the wooden piece 211 must be taken out from the raw wood so as to have a flat grain surface. Hence, at the taking out of the wooden piece 211 from the raw wood 50, the wooden piece 211 is taken out so that the curvature of the side surface of the wooden piece 211 is generally larger than the curvature of the grain 50G as shown in FIG. 26.

A wooden piece other than a flat grain wooden piece is employable as the wooden piece 211. For example, a straight grain wooden piece, a wooden piece with an intermediate grain pattern between the flat grain and the straight grain, or a end grain wooden piece are employable. Thus, a manner of taking out a wooden piece to be processed from the raw wood 50 can be determined according to various conditions such as a purpose of use of a compressed wood product manufactured from the wooden piece, required strength, appearance, or the like of the compressed wood product.

Subsequently, the wooden piece 211 taken out as described above is compressed (compression process). Prior to the compression process, the wooden piece 211 is left in the same water vapor atmosphere of high temperature and high pressure as in the first embodiment for a predetermined time period. Thus, the wooden piece 211 absorbs water in excess to be softened. Alternatively, the wooden piece 211 may be heated by high-frequency electromagnetic waves such as microwaves before compression, for example.

FIG. 27 is a perspective view of a structure of main parts of a processing apparatus according to the third embodiment of the present invention. A processing apparatus 200 shown in FIG. 27 includes an upper mold 231 (first mold) that applies compressive force to the wooden piece 211 from above the wooden piece 211 to be processed, a lower mold 241 (second mold) that applies compressive force to the wooden piece 211 from below the wooden piece 211, and a guide mold 251 fixedly disposed on an upper surface of the lower mold 241 to guide the upper mold 231 in a moving direction.

FIG. 28 is a sectional view of a structure of main parts of the processing apparatus 200 and schematically showing how the compression process of the wooden piece 211 is performed, and is a vertical sectional view along line K-K of FIG. 27. Hereinbelow, the structure of the main parts of the processing apparatus 200 will be described in detail with reference to FIGS. 27 and 28.

The upper mold 231 includes a rubber mold 232 that is made of a material such as silicon rubber (elastic body) and that deformably abuts the internal surface 211 b which is one of the surfaces of the wooden piece 211, and a substantially rectangular solid movable metal mold 233 that is adhered to the upper end of the rubber mold 232 and movable in the vertical direction. The rubber mold 232 includes a protrusion 234 that protrudes downwards and abuts at least a portion of the internal surface 211 b of the wooden piece 211, and an end surface pressing portion 235 that holds an end surface 211 c of the wooden piece 211 and applies compressive force to the end surface 211 c in a direction substantially perpendicular to the thickness direction of the end surface 211 c at compression. In FIG. 28, the section of the wooden piece 211 is shown reversed from the section in FIG. 25, and the internal surface 211 b of the wooden piece 211 is shown above the external surface 211 a.

The lower mold 241 is implemented with a metal and has a depression 242 which fits the external surface 211 a of the wooden piece 211. The shape of the depression 242 matches with the shape of the external surface of the main plate 12 a of the compressed wood product 12.

The guide mold 251 is of a hollow rectangular solid shape made of metal or hard resin. A guide 252 is formed with inner surfaces of the guide mold 251, and is formed when the rectangular solid constituting a main body of the guide mold 251 is penetrated from one surface to the other of the two surfaces facing each other with a shape substantially of square cone platform. The space thus formed in the guide mold 251 is tapered downward so that the opening on an upper surface is larger in area than the opening on a lower surface, when the processing apparatus 200 is assembled. Thus, a rectangle formed as a cross section of the guide 252 and a horizontal plane gets smaller downwards in a vertical direction. The opening on the lower surface of the guide 252 is of a substantially rectangular form which is congruent with a shape of an opening on an upper end of the depression 242 of the lower mold 241. The guide mold 251 and the lower mold 241 are assembled so that the respective congruent openings are superposed. Alternatively, the guide mold 251 and the lower mold 241 can be formed as an integral part.

At the compression of the wooden piece 211, the upper mold 231 is inserted from the opening on the upper surface of the guide 252, i.e., from the opening with a larger area. As mentioned above, the substantially rectangular form on the cross section of the guide 252 and the horizontal plane gets smaller downward in the vertical direction. Hence, the outer periphery of the upper mold 231 abuts the guide 252 during the descent thereof, and after the abutment, the outer periphery of the upper mold 231 slides along the guide 252 down to a predetermined position.

In FIG. 28, an angle of inclination of the guide 252 substantially matches with an angle of inclination of the neighborhood of the upper end portion of the depression 242, and the surfaces thereof are smoothly aligned. More generally, it is satisfactory if only the opening on the lower surface of the guide 252 has substantially the same shape as the opening on the upper end of the depression 242, and there is no step at the boundary therebetween. The shape of the hollow shape depends on a finished shape of the compressed wood product to be manufactured. Depending on a desired finished shape, the hollow shape may substantially be of a frustum shape, such as a truncated pyramid, a circular truncated cone, an ellipsoidal truncated cone, or the like.

Next, the compression process performed by the processing apparatus 200 with the above-described structure will be described with reference to FIG. 28. The wooden piece 211 rests in a position with an outer periphery of the end surface 211 c abutting and supported by the guide 252. Thereafter, when the upper mold 231 is lowered, the lower end portion of the protrusion 234 first abuts the central portion of the internal surface 211 b of the wooden piece 211. In the state as shown in FIG. 28, the shape of the internal surface 211 b does not completely match with the shape of the protrusion 234, and hence, there is a gap between the periphery of the internal surface 211 b and the protrusion 234.

FIG. 29 is a sectional view of the upper mold 231 on the way to being lowered down from the state shown in FIG. 28. As shown in FIG. 29, as the upper mold 231 is lowered, the rubber mold 232 itself is pressed by the movable metal mold 233 and the wooden piece 211 to be deformed, and a region of the internal surface 211 b brought into contact with the rubber mold 232 gradually expands from the central portion to the peripheral portion of the surface of the wooden piece 211. Simultaneously, the end surface pressing portion 235 of the rubber mold 232 abuts the end surface 211 c to apply compressive force thereto in a direction perpendicular to the thickness direction of the end surface 211 c. As a result, a region on which the compressive force acts on the surface of the wooden piece 211 gradually expands as the upper mold 231 is lowered, whereby the gap between the external surface 211 a and the lower mold 241, and the gap between the internal surface 211 b and the rubber mold 232 gradually decreases with the deformation. Then, the thickness of the wooden piece 211 becomes smaller first in the neighborhood of the central portion and then in the peripheral portion, and eventually the entire thickness decreases.

Here, to realize a smooth sliding movement of the outer periphery of the rubber mold 232 along the guide 252, the surface of the guide 252 may be coated with a material such as Teflon (registered trademark) or the like in advance. Then, the wooden piece 211 also slides along the surface of the guide 252 more smoothly, whereby the generation of cracks at the descent of the wooden piece 211 can be more surely prevented. Here, the outer periphery of the rubber mold 232 may be coated with a material such as Teflon (registered trademark).

As described above, when the rubber mold 232 which is deformable through the application of external forces is applied in the upper mold 231, the rubber mold 232 itself is deformed at the time of compression to alleviate a sudden deformation of the wooden piece 211. Further, with the pressure applied by the end surface pressing portion 235 to the end surface 211 c, the expansion of the wooden piece 211 in a direction perpendicular to the thickness direction can be restricted. Hence, even when the deformation of the wooden piece 211 is significant, the tensile force does not act on the wooden piece 211. Hence, the wooden piece 211 can be deformed according to compressive force alone, and the generation of crack or the like on the wooden piece 211 can be prevented.

Thereafter, the rubber mold 232 completely fills the gap between the wooden piece 211 and the rubber mold 232, and the lowering of the movable metal mold 233 is stopped when the rubber mold 232 applies a predetermined compressive force to the wooden piece 211. FIG. 30 is a sectional view of the wooden piece 211 in the compression process where the deformation of the wooden piece 211 is nearly finished. In the state as shown in FIG. 30, a uniform compressive force is applied from the rubber mold 232 to the entire wooden piece 211 regardless of the position due to characteristics of the rubber mold 232 as an elastic body. After being left for the predetermined time period in the state as described above, the upper mold 231 is separated from the lower mold 241.

Subsequently, a metal mold (hereinafter referred to as a shaping metal mold) which is employed for shaping and is different from the upper mold 231 is lowered down in the same water vapor atmosphere as in the compression process, and the wooden piece 211 is sandwiched between the shaping metal mold and the lower mold 241 to be shaped (shaping process). FIG. 31 is a sectional view of the wooden piece 211 being compressed in the shaping process where the deformation of the wooden piece 211 is nearly finished, and is a vertical sectional view along the same section as in FIG. 28 or the like.

A shaping metal mold 261 which applies compressive force to the wooden piece 211 from above in the shaping process has a protrusion 262 which fits the internal surface 211 b of the wooden piece 211. The protrusion 262 precisely corresponds with the internal surface of the compressed wood product 12 in shape, and is formed so that the portion which is not sufficiently compressed by the rubber mold 232 in the above-described compression process, for example, the vicinity of the end surface 211 c of the wooden piece 211, is shaped. After the wooden piece 211 is left in the compressed state as shown in FIG. 31 for a predetermined time period, the lower mold 241 is separated from the shaping metal mold 261 to release the wooden piece 211 from compression and water vapor atmosphere, and then the wooden piece 211 is dried. Thus, the compressed wood product 12 is finished.

The thickness r₄ of the compressed wood product 12 thus obtained according to the method of processing described above is approximately 30% to 50% of the thickness r₅ of the uncompressed wooden piece 211 taken out from the raw wood 50. In other words, the compression rate (r₅−r₄)/r₅ of the wooden piece is approximately in a range of 0.5 to 0.7. The compression rate in each process can be varied with the wood species of the wooden piece 211, the purpose of use of the compressed wood product 12 or the like. For example, the thickness may not be substantially changed and only the shape of the wooden piece may be notably changed in the compression process, and the wooden piece is compressed mainly in the thickness direction in the shaping process.

Depending on the shape and the purpose of use of the compressed wood product to be processed, a desired three-dimensional shape of the wooden piece may be obtained with a sufficient accuracy merely by the compression process. Then, the shaping process is not always necessary.

When the upper mold 231 or the shaping metal mold 261 are moved with respect to the lower mold 241 in the vertical direction, the processing apparatus 200 may be provided with a driving unit for electrically driving the upper mold 231 or the shaping metal mold 261, and a control unit for controlling the drive of the driving unit, so that the upper mold 231 or the shaping metal mold 261 can be electrically driven and the compressive force applied to the wooden piece 211 can be controlled. Alternatively, the upper mold 231 or the shaping metal mold 261 may be screwed on the lower mold 241, so that the vertical movement of the upper mold 231 or the shaping metal mold 261 relative to the lower mold 241 can be realized with manual or automatic screwing, and the compressive force applied to the wooden piece 211 can be controlled.

Still alternatively, the surface of the wooden piece to be processed may be shaped by cutting in the shaping process. The cutting process is suitable when the wooden piece after compression process has a knurl portion which remains thicker than other portions of the wooden piece and which is desired to be flat.

The water vapor atmosphere of high temperature and high pressure in the compression process can be realized, for example, inside a pressure container. Then, since there is only a limited space in the pressure container, a stroke of the mold or the metal mold to be driven cannot be set long. When the upper mold 231 as described above is employed, however, since the rubber mold 232 is deformed, the stroke can be set longer than an ordinary metal mold, whereby the compressive force can be more freely applied even in a limited space.

According to the third embodiment of the present invention as described above, the provision of the upper mold which includes the rubber mold at a portion abutting the wooden piece, the guide mold which guides the upper mold in the moving direction, and the lower mold which sandwiches the wooden piece with the upper mold and applies the compressive force to the wooden piece for applying compressive force to the wooden piece, allows for the shaping of the wooden piece without the generation of cracks even when the deformation through the compression is significant.

Further, according to the third embodiment, since the upper mold includes the rubber mold as a portion abutting the wooden piece, the rubber mold is deformed at the time of compression so as to apply uniform compressive force to the entire surface of the wooden piece. Hence, the density of the wooden piece can be made uniform regardless of the shape of the wooden piece to be processed and the compressed wooden piece can be granted with a uniform strength.

Further, according to the third embodiment, at least the surface abutting the lower metal mold can be precisely deformed through the compression process, and hence, when the shaping accuracy is required only for one side surface of the compressed wood product, the processing of wood can be finished with the compression process. Hence, various processing can be performed according to the purpose of use, the required appearance, or the like of the compressed wood product.

Alternatively, the upper mold may be implemented with a mold formed from a viscoelastic body or the like containing more general polymer gel. In other words, a material having at least one of viscosity and elasticity may be employed as a material of the upper mold in a portion abutting the wooden piece to be processed.

FIG. 32 is a perspective view of a structure of an upper mold (first mold) constituting a part of a processing apparatus according to a fourth embodiment of the present invention. FIG. 33 is a sectional view along line L-L of FIG. 32. An upper mold 371 shown in FIGS. 32 and 33 includes a substantially rectangular solid main body 372, and a plurality of end surface pressing portions 373 that protrudes from side surfaces of the main body 372 in such a manner as to be freely movable in a direction of an outer periphery, thereby abuts the end surface of the wooden piece at the compression, and applies compressive force to the wooden piece in a direction substantially perpendicular to the thickness direction of the abutting end surface. The main body 372 includes a holder 374 provided on the side surface to hold each end surface pressing portion 373, and a bottom surface portion 375 which abuts the surface of the wooden piece to be processed and applies compressive force thereto. The end surface pressing portion 373 is also connected to one end of a resilient member 376 such as a spring whose another end is fixed to the holder 374, and is subjected to a spring force in an outward direction from the side surface of the main body 372.

FIG. 34 is a diagram of a structure of main parts of the processing apparatus according to the fourth embodiment and schematically showing how the compression process of the wooden piece 211 is performed, and is a vertical sectional view corresponding to FIG. 28 of the third embodiment. A processing apparatus 300 shown in FIG. 34 includes an upper mold 371 having the above-described structure, the lower mold 241, and the guide mold 251. The structures of the lower mold 241 and the guide mold 251 are the same as described in the third embodiment. Further, the upper mold 371 is driven in the same manner as the upper mold 231 described above. The wooden piece 211 to be processed is taken out from the raw wood 50 similarly to the third embodiment described above, is left in the water vapor atmosphere of high temperature and high pressure described above, and is softened prior to the compression.

In the same water vapor atmosphere as described above, the upper mold 371 of the processing apparatus 300 is lowered down so that a portion of the bottom surface portion 375 starts to abut the internal surface 211 b of the wooden piece 211. Specifically, a curved peripheral portion of the bottom surface portion 375 abuts the peripheral portion of the internal surface 211 b. Further, a portion (neighborhood of the upper end portion) of the end surface 211 c abuts a bottom surface of the end surface pressing portion 373. In the state as shown in FIG. 34, since the shape of the internal surface 211 b does not match with the shape of the bottom surface portion 375, a gap is formed between the central portion of the internal surface 211 b and the central portion of the bottom surface portion 375, and between the end surface 211 c and the bottom surface of the end surface pressing portion 373, or the like.

FIG. 35 is a sectional view of the upper mold 371 on the way to being lowered down from the state shown in FIG. 34. When the upper mold 371 is lowered down from the state as shown in FIG. 34, the outer peripheral portion of the bottom surface of the end surface pressing portion 373 abuts the surface of the guide 252 to receive a drag. Then the end surface pressing portion 373 gradually recedes in a direction of center of gravity of the main body 372 into the holder 374 against the spring force applied by the resilient member 376. The lower end of the end surface pressing portion 373 abuts the end surface 211 c of the wooden piece 211 and applies compressive force to the end surface 211 c in a direction substantially perpendicular to the thickness direction of the end surface 211 c. Hence, the wooden piece 211 is lowered down and gradually deformed while the edge thereof slides down on the surface of the guide 252. In the process, a contact area between the bottom surface portion 375 and the internal surface 211 b of the wooden piece 211 increases, and a contact area between the bottom surface of the end surface pressing portion 373 and the end surface 211 c also increases. Then, a state shown in FIG. 35 is realized, i.e., the neighborhood of the central portion of the external surface 211 a comes to abut the depression 242 of the lower mold 241.

Thereafter, as the upper mold 371 is further lowered down, a region where compressive force acts on the surface of the wooden piece 211 gradually expands, and the gap between the external surface 211 a and the lower mold 241, and the gap between the internal surface 211 b and the upper mold 371 further gradually decrease.

FIG. 36 is a sectional view of the wooden piece 211 where the deformation of the wooden piece 211 is nearly finished as a result of the accession of the upper mold 371 down to a lowermost position. In the state as shown in FIG. 36, the bottom surface of the end surface pressing portion 373 faces and contacts with the end surface 211 c without a gap therebetween, and the bottom surface portion 375 and the internal surface 211 b also contact with each other without a gap therebetween. When the wooden piece 211 is held in the state as shown in FIG. 36 for a predetermined time period, at least a portion sandwiched between the end surface pressing portion 373 and the depression 242 in the wooden piece 211 can be deformed into a predetermined shape.

A portion which is not pressed by the end surface pressing portion 373 in the end surface 211 c may be formed in a distorted shape due to the influence of wooden components squeezed out from a portion pressed by the end surface pressing portion 373 in the compression process described above. Then, similarly to the third embodiment, such a portion may be shaped by the shaping metal mold or the unevenness of the end surface 211 c may be planarized by cutting or the like.

In the fourth embodiment, since the upper mold 371 and the lower mold 241 are both metal molds, the surface shape of the molds themselves do not change except the changes in the shape of the upper mold 371 caused by the retreat of the end surface pressing portion 373. Hence, for the prevention of the crack of the wooden piece 211 in the compression, a degree of freedom must be provided to allow a portion of wooden component to escape into an open space. Hence, compressive force is preferably not applied by the end surface pressing portion 373 during the compression process to a portion where the escaping wooden components tend to gather from two directions in the compression, for example, to a portion which forms a boundary between the side plate 12 b and the side plate 12 c of the compressed wood product 12 after processing. Thus, the number, the size, or the position of the end surface pressing portion 373 provided in the upper mold 371 may be determined as appropriate according to the finished shape of the wooden piece 211, i.e., the shape of the compressed wood product.

According to the fourth embodiment of the present invention as described above, similarly to the third embodiment, the provision of the metal upper mold which includes the plurality of end surface pressing portions that are movable toward outer periphery, the guide mold which guides the upper mold in the moving direction, and the lower mold which sandwiches the wooden piece with the upper mold and applies the compressive force to the wooden piece for applying compressive force to the wooden piece, allows for the shaping of the wooden piece without the generation of cracks even when the deformation by the compression is significant.

In addition, according to the fourth embodiment, since the upper mold is also made of metal, compression forming can be performed with higher form accuracy also on a portion of the wooden piece which abuts the upper mold.

Though the first to the fourth embodiments are described as exemplary embodiments of the present invention, it should be understood that the present invention is not limited thereto. The present invention covers various embodiments not particularly described above, and various modifications in design or the like are realizable within the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. A processing apparatus for processing a wooden piece into a predetermined three-dimensional shape, comprising: a first mold made of a material having at least one of viscosity and elasticity at least in a portion that abuts a surface of the wooden piece; and a second mold made of metal sandwiching the wooden piece with the first mold to apply compressive force on the wooden piece.
 2. The processing apparatus according to claim 1, wherein the first mold includes a protrusion that abuts the surface of the wooden piece at compression of the wooden piece, and applies compressive force on the surface of the wooden piece while gradually expanding an abutting region of the surface from a central portion to a peripheral portion; and an end surface pressing portion that abuts an end surface of the wooden piece at compression of the wooden piece, and applies compressive force on the wooden piece in a direction substantially perpendicular to a thickness direction of the end surface.
 3. The processing apparatus according to claim 1, further comprising a guide mold that guides the first mold in a moving direction.
 4. The processing apparatus according to claim 3, wherein the guide mold includes a guide which is formed as a substantially frustum-shaped penetration of a main body of the guide mold, and a smaller opening of openings formed at ends of the guide has a same shape as an opening of the second mold.
 5. The processing apparatus according to claim 3, wherein the first mold can be inserted into the guide mold from a larger opening of the openings formed at the ends of the guide.
 6. The processing apparatus according to claim 3, wherein the guide mold is formed integrally with the second mold.
 7. A wood processing mold for processing a wooden piece into a predetermined three-dimensional shape by sandwiching the wooden piece with a metal mold to apply compressive force thereto, the wood processing mold comprising: a protrusion that abuts the surface of the wooden piece at compression of the wooden piece, and applies compressive force on the surface of the wooden piece while gradually expanding an abutting region of the surface from a central portion to a peripheral portion; and an end surface pressing portion that abuts an end surface of the wooden piece at compression of the wooden piece, and applies compressive force on the wooden piece in a direction substantially perpendicular to a thickness direction of the end surface, wherein the protrusion and the end surface pressing portion are made of a material having at least one of viscosity and elasticity.
 8. A method of processing wood for processing a wooden piece into a predetermined three-dimensional shape by applying compressive force on the wooden piece, the method comprising performing a compression process in which the wooden piece is compressed while a region of the wooden piece on which the compressive force acts is gradually expanded from a central portion to a peripheral portion.
 9. The method according to claim 8, further comprising, prior to the compression process, performing a primary compression process in which the wooden piece is sandwiched and compressed between a pair of metal molds.
 10. The method according to claim 9, wherein an average compression rate of the wooden piece in the primary compression process is smaller than an average compression rate of the wooden piece in the compression process.
 11. The method according to claim 9, wherein the pair of metal molds is formed so that the compressive force is applied at least on a portion of the wooden piece where a thickness direction of the wooden piece is substantially parallel to a direction of action of the compressive force.
 12. The method according to claim 8, further comprising performing a shaping process in which the wooden piece compressed in the compression process is shaped into the three-dimensional shape.
 13. The method according to claim 12, wherein the shaping process includes a finishing compression process in which the wooden piece is compressed.
 14. The method according to claim 12, wherein the shaping process includes a cutting process in which a surface of the wooden piece is cut.
 15. A method of processing wood for processing a wooden piece into a predetermined three-dimensional shape by applying compressive force on the wooden piece, the method comprising performing a compression process in which the wooden piece is sandwiched and compressed between a first mold made of a material having at least one of viscosity and elasticity at least in a portion that abuts a surface of the wooden piece, and a second mold made of metal.
 16. The method according to claim 15, further comprising, prior to the compression process, performing a primary compression process in which the wooden piece is sandwiched and compressed between a pair of metal molds.
 17. The method according to claim 16, wherein an average compression rate of the wooden piece in the primary compression process is smaller than an average compression rate of the wooden piece in the compression process.
 18. The method according to claim 16, wherein the pair of metal molds is formed so that the compressive force is applied at least on a portion of the wooden piece where a thickness direction of the wooden piece is substantially parallel to a direction of action of the compressive force.
 19. The method according to claim 15, further comprising performing a shaping process in which the wooden piece compressed in the compression process is shaped into the three-dimensional shape.
 20. The method according to claim 19, wherein the shaping process includes a finishing compression process in which the wooden piece is compressed.
 21. The method according to claim 19, wherein the shaping process includes a cutting process in which a surface of the wooden piece is cut. 